Following a four-year investigation which found that pharmaceutical giant GlaxoSmithKline had held back evidence about the link between its controversial antidepressant Seroxat and the high risk of suicidal thoughts among teenagers, the British government has promised today to tighten laws requiring drug companies to disclose data from clinical trials.

"We will take immediate steps to ensure the law is strengthened further, so that there can be no doubt as to companies' obligations to report safety issues," Kent Woods, chief executive of the Medicines and Healthcare products Regulatory Agency (MHRA), said in a statement on Thursday, according to Reuters.

The Medicines and Healthcare products Regulatory Agency received data from clinical trials in May 2003 showing that patients under 18 had a higher risk of suicidal behavior if they were treated with Seroxat than if they received a placebo. These data also showed that the drug was not effective for treating depression in children and adolescents.

Woods said the MHRA was disappointed that GSK had not given them information earlier.

“I remain concerned that GSK could and should have reported this information earlier than they did. All companies have a responsibility to patients, and should report and adverse data signals to us as soon as they discover them. This investigation has revealed important weaknesses in the drug safety legislation in force at the time,” he said.

Through GSK broke the rules, it would not face charges because the legislation in place at the time was not sufficiently strong.

Following on this incident which could have had bad repercussions, the public health minister, Dawn Primarolo, said new legislation would be introduced by the end of the year to ensure drugs companies pass on results of clinical trials as soon as the alarm is raised about one of their medicines.

"Companies that conduct clinical trials should not compromise people's health by withholding information," she said.

There was no immediate reaction from GSK.